System for controlling a tensioning carriage for a traction cable for an ingot truck

ABSTRACT

This invention relates to steelworks installations provided with an ingot truck drawn by a cable. The invention relates to the system for controlling the cable-tensioning carriage. It is characterized in that the said system comprises a hydraulic jack whose two elements, i.e. cylinder and piston, are respectively connected to a fixed part of the installation and attached to the tensioning carriage, one of the jack chambers communicating with a pressure circuit while the other chamber communicates with a liquid tank via two conduits each containing a valve which opens completely to supply the corresponding chamber and closes partially to allow liquid to escape from said chamber, means for limiting the rate of flow being provided for such escape. This system eliminates any danger of cable oscillation.

United States Patent [72) inventor Andre Nectoux Le Creusot, France [21] AppLNo. 815,480 [22] Filed Apr. 11, 1969 [45} Patented Apr. 13, 1971 [73] Assignee Societe Des Forges Et Ateliers Du Creusot Paris, France [32] Priority May 6, 1968 [33] France I l 1 150649 [54] SYSTEM FOR CONTROLLING A TENSIONING CARRIAGE FOR A TRACTION CABLE FOR AN INGOT TRUCK 1 Claim, 2 Drawing Figs.

[52] US. Cl 60/51, 92/12, 254/172, 254/189 [51] Int. Cl F03c 1/16 [50] Field of Search 254/ l 72, 189; 92/8-12; 267/64, 65; 187/26; 60/51 [56] References Cited UNITED STATES PATENTS 2,827,763 3/1958 Govan et al 254/172 2,861,794 1 H1958 Beck 267/64 3,176,466 4/1965 Pinsenschaum 60/5 1 3,309,065 3/1967 Prudl-lomme et al 254/189 3,314,657 4/1967 PrudHomme et al. 254/189 3,395,777 8/1968 Rodosta 254/189 3,208,728 9/1965 Parks 254/172 FOREIGN PATENTS 623,228 5/ 1949 Great Britain 187/26 Primary Examinen-Harvey C. Homsby Assistant ExaminerMerle F. Maffei Att0rneyCameron, Kerkam & Sutton ABSTRACT: This invention relates to steelworks installations provided with an ingot truck drawn by a cable. The invention relates to the system for controlling the cable-tensioning carriage. It is characterized in that the said system comprises a hydraulic jack whose two elements, i.e. cylinder and piston, are respectively connected to a fixed part of the installation and attached to the tensioning carriage, one of the jack chambers communicating with a pressure circuit while the other chamber communicates with a liquid tank via two conduits each containing a valve which opens completely to supply the corresponding chamber and closes partially to allow liquid to escape from said chamber,-means for limiting the rate of flow being provided for such escape. This system eliminates any danger of cable oscillation.

Pmmd A ril 13, 1911 3,514,999

FIG!

O W K 6 SYSTEM FOR CONTROLLING A 'IENSIONING CARRIAGE FOR A TRACTION CABLE FOR AN INGOT TRUCK The invention relates to a system for controlling a tensioning carriage for a traction cable for an ingot truck.

Installations are known for driving an ingot truck by means of a traction cable passing over a positive-engagement pulley, e.g. a Koepe pulley, rotation of which is provided by a motor. For positive engagement to be obtained and the drive to be correct, the cable must be kept under tension. To this end, counterweights are generally used, which act on a movable carriage bearing a cable return pulley. In some cases there is a risk of the cable oscillating, particularly in the event of changes of the state of operations as transmitted to the car movement, and it is therefore necessary to provide a shockabosrbing jack which acts on the said carriage.

The invention relates to a hydraulic system which acts on the movable carriage and provides cable tensioning and absorbs any oscillations, and this enables the conventional counterweights and the pit required for their movement to be eliminated.

According to the invention, the system comprises a hydraulic jack whose two elements, i.e. cylinder and piston, are respectively connected to a fixed part of the installation and attached to the tensioning carriage, one of the jack chambers communicating with a pressure circuit while the other chamber communicates with a liquid tank via two conduits each containing a valve which opens completely to supply the corresponding chamber and closes partially to allow liquid to escape from said chamber, means for limiting the rate of flow being provided for such escape.

The invention will now be described in greater detail with reference to a specific embodiment given by way of example and illustrated in the drawings.

FIG. I is a highly diagrammatic general view of an installation for the traction of an ingot truck comprising the system according to the invention.

FIG. 2 diagrammatically illustrates the jack for controlling the tensioning carriage and its hydraulic supply.

FIG. 1 illustrates an ingot truck 1 operated by an endless cable 2 passing over a positive'engagement drive pulley 3. The endless cable 2 passes over a pulley 4 borne by a carriage 5 which is pulled to the right to provide tension on the traction cable 2. This tension is produced by a hydraulic jack 6.

The jack 6 and its supply system are shown in greater detail in FIG. 2. The jack comprises a cylinder 6 with a piston 7 movable therein. The piston rod 8 is attached by a link 9 to the carriage 5 while the cylinder 6 is connected to a fixed part of the installation.

The link 9 may have a number of apertures 10 for fixing to the carriage 5 in order to adjust the carriage distance and the cable tension, having regard to the position of the piston 7 inside the cylinder 6. During operation, the cable 2 tends to elongate after a certain time and adjustment is necessary in this respect. This system thus enables use to be made of a jack having a reduced travel.

The jack 6 is fed by a hydraulic circuit. The high-pressure chamber 11 of the jack communicates with a hydraulic accumulator 13 via conduit 12. Pressure is maintained in the conduit 12 by a pump 14 which delivers to the conduit via a nonretum valve 15 which allows the conduit to be supplied withpressure liquid and prevents the pump 14 from being subjected to the liquid pressure when the pump is stopped.

The pump is fed with liquid from a tank 16 which is airtight and pressurized so that the pump 14 is regularly supplied from the liquid in the tank 16.

The pump I4 is started only when the liquid level in the accumulator 13 drops. To this end, a level detector (or pressure detector depending on the type of accumulator) 17 is provided in combination with the accumulator 13. This detector results in the pump motor 18 starting when the level in the accumulator drops, and stops the motor 18 as soon as the level has returned to normal.

A pressostat 19 connected to conduit 12 completely stops the installation in the event of an abnormal pressure drop in the installation.

The chamber 20 of jack 6 communicates with the liquid tank I6 via conduit 21.

Each of the conduits I2 and 21 is provided with a box 22 and 23 respectively, containing a valve 24, 25 opening completely in the event of the liquid tending to penetrate into the corresponding chamber 11, 20. On the other hand, the valves 24 and 25 partially close when the liquid tries to escape from the corresponding chamber.

The closure of the valves 24 and 25 -is limited by adjustable points 26, 27, free adjustment being possible so that the leakage flow of the liquid from the jack chambers can be adjusted.

The installation is completed by a cock 28 in the conduit 21, by a conduit 29 connecting the two chambers 11 and 20 and containing a cock 30.

For normal operation, cock 30 is closed and cock 28 is open. When the pump 14 has supplied the circuit and more particularly the conduit 12 so that the chamber 11 is under pressure, .the piston 7 tends to move to the right and the carriage 5 tensions the cable 2. Liquid arrives into the chamber 11 freely via the valve box 22, the valve 24 being completely open. When, however, the liquid tends to escape from the chamber 20, valve 25 partially closes, the escape being limited by the point 27. The leakage from chamber 20 is thus retarded and oscillation of the cable is thus eliminated.

In the event of an oscillation tending to occur with the possibility of moving the piston 7 to the left, the valve 24 would partially close, the escape being limited by the point 26, and the liquid escaping from chamber 11 would be throttled by the valve 24 so that the oscillations would be practically eliminated.

From the above it will be apparent that irrespective of the forces exerted on the carriage 5 they cannot cause any oscillation of the installation, since such oscillation is eliminated by throttling of the liquid escaping from a chamber.

If it is required to return the carriage 5 t0 the front position, e.g. for replacing ortaking up any elongation of the cable, the cock 28 can be closed and cock 30 opened.

Of course the invention is not limited to the abovedescribed embodiment details of which may be modified without departing from the scope of the invention.

lclaim:

l. A system for controlling a tensioning carriage for a trac tion cable for an ingot truck comprising a hydraulic jack, a cylinder and a piston therein for said jack, said cylinder being fixed and immovable, said piston being connected to the tensioning carriage, a jack chamber in said cylinder on each side of said piston, a pressure circuit opening into one of said jack chambers, a liquid tank, a conduit connecting said liquid tank to the other of said jack chambers, a valve in said pressure circuit, a valve in said conduit, said valves when open supplying fluid to the respective one of said jack chambers, and when partially closed allowing escape of liquid from the respective one of said jack chambers and limiting the rate of flow of escaping liquid, pump means supplying liquid under pressure to said pressure circuit from said liquid tank through a nonretum valve, a hydraulic accumulator in said pressure circuit, a liquid level detector in said accumulator, a motor driving said pump means and motor-starting means actuated by said level detector when the liquid level in said accumulator drops. 

1. A system for conTrolling a tensioning carriage for a traction cable for an ingot truck comprising a hydraulic jack, a cylinder and a piston therein for said jack, said cylinder being fixed and immovable, said piston being connected to the tensioning carriage, a jack chamber in said cylinder on each side of said piston, a pressure circuit opening into one of said jack chambers, a liquid tank, a conduit connecting said liquid tank to the other of said jack chambers, a valve in said pressure circuit, a valve in said conduit, said valves when open supplying fluid to the respective one of said jack chambers, and when partially closed allowing escape of liquid from the respective one of said jack chambers and limiting the rate of flow of escaping liquid, pump means supplying liquid under pressure to said pressure circuit from said liquid tank through a nonreturn valve, a hydraulic accumulator in said pressure circuit, a liquid level detector in said accumulator, a motor driving said pump means and motor-starting means actuated by said level detector when the liquid level in said accumulator drops. 